Quantum Phase Transition as a Promising Route to Enhance the Critical Current in Kagome Superconductor CsV$_{3}$Sb$_{5}$

TL;DR

This study demonstrates that employing quantum phase transitions via hydrostatic pressure can significantly enhance the critical current in the kagome superconductor CsV3Sb5, revealing a quantum anomaly linked to charge density wave suppression.

Contribution

It introduces a novel approach of using quantum phase transition to boost critical current in a kagome superconductor, highlighting the role of quantum fluctuations near the CDW phase transition.

Findings

Critical current peaks at zero-temperature near the CDW suppression point.

Pressure-tuned quantum anomaly observed at approximately 20 kbar.

Enhanced quantum fluctuations linked to charge density wave suppression.

Abstract

Developing strategies to systematically increase the critical current, the threshold current below which the superconductivity exists, is an important goal of materials science. Here, the concept of quantum phase transition is employed to enhance the critical current of a kagome superconductor CsV$_3$Sb$_5$, which exhibits a charge density wave (CDW) and superconductivity that are both affected by hydrostatic pressure. As the CDW phase is rapidly suppressed under pressure, a large enhancement in the self-field critical current ($I_{\rm c,sf}$) is recorded. The observation of a peak-like enhancement of $I_{\rm c,sf}$ at the zero-temperature limit ($I_{\rm c,sf}(0)$) centred at $p^*\approx 20$~kbar, the same pressure where the CDW phase transition vanishes, further provides strong evidence of a zero-temperature quantum anomaly in this class of pressure-tuned superconductor. Such a peak in $I_{\rm c,sf}(0)$ resembles the findings in other well-established quantum-critical superconductors, hinting at the presence of enhanced quantum fluctuations associated with the CDW phase in CsV$_3$Sb$_5$.